@mixin bgIcon($url) {
  background: url($url + ".png");
  @media (-webkit-min-device-pixel-ratio: 3), (min-device-pixel-ratio: 3) {
    background-image: url($url + '@2x.png');
  }
}

@mixin gradualChange() {
  background: -webkit-linear-gradient(#BF9E63, #DCBE87); /* Safari 5.1 - 6.0 */
  background: -o-linear-gradient(#BF9E63, #DCBE87); /* Opera 11.1 - 12.0 */
  background: -moz-linear-gradient(#BF9E63, #DCBE87); /* Firefox 3.6 - 15 */
  background: linear-gradient(#BF9E63, #DCBE87); /* 标准的语法 */
}
